PHNOM PENH - Opposition leader Sam Rainsy on Thursday urged Cambodian authorities to reopen an investigation into a deadly bridge stampede during the Water Festival in 2010.

Sam Rainsy, president of the Cambodia National Rescue Party, made his statement as the opposition held a memorial service for the more than 350 people who died during the stampede, when festival goers panicked on a crowded bridge.

“We must find those who are responsible and reveal the truth,” he said.

Critics say city authorities and police failed to adequately control the crowds during the festival, which brings millions of people to Phnom Penh for boat races and other celebrations. A government investigation found no wrongdoing in the incident.

The city of Phnom Penh is planning to hold its own memorial service on Friday.

At Thursday’s ceremony, eight monks and 200 people took part in remembering the fatal stampede and its victims.

“I regret the loss of my son,” said Soun Ye, 48, the mother of Soum Chan Thouen, 24, who died on the bridge. “He was my only son of two of my children, and I relied on him.”

Government spokesman Phay Siphan said the investigation into the stampede was “closed.” The investigation found no blame in the accident, he said. Instead, he said, the investigation found blame in “only a stampede.”